1. Field of the Invention
The present invention relates to an image processing apparatus and an image processing method. In particular, the present invention relates to a technique for detecting an object and determining a photographing range.
2. Description of the Related Art
Conventionally, there is a technique for detecting an object region and determining and adjusting the photographing range to cover the entire object region (hereinafter to be referred to as auto-framing). For example, Japanese Patent Application Laid-Open No. 60-208184 discusses a technique in which a camera used in a video conference previously photographs a conference room before the start of the conference as a background image. Positions of the participants of the conference are then detected based on a difference between the background image and the image at the start of the conference, and zoom control is thus performed to include all participants of the conference in the photographing range.
Further, Japanese Patent Application Laid-Open No. 2005-294951 discusses a digital image printing system in which a face region is detected, and zoom control is then performed to include the entire face region in the photographing range. Furthermore, Japanese Patent Application Laid-Open No. 2007-189717 discusses a technique for detecting that a person has taken a seat and then once photographing the conference room. If the photographed face position is appropriate, the camera position is adjusted, and the camera then waits for a photograph instruction to be input by a user.
In a case where the video conference is about to begin, the person to be the object is busy preparing for the conference and may not be fully conscious of the camera, so that the person may face down or sideways. However, since the face can only be detected when facing the front in face detection, the face becomes undetected in the above-described case.
Further, other objects in the conference room may be erroneously detected as the face of a person during the conference. Furthermore, if the object moves, an object position may not be correctly detected. To solve such problems, it becomes necessary for the participants (i.e., objects) to stare at the camera without moving, which is burdensome for the users of the video conference system.
Moreover, in the case of a video conference, the participants each behave differently from arrival at the conference room to being seated. Conventionally, it thus becomes necessary for the user to instruct auto-framing to start after all participants have sat down and it is confirmed that they are all looking at the camera.
Originally, auto-framing is advantageous in that the users can perform other tasks such as preparation for the conference while auto-framing is being performed. It is thus desirable for auto-framing to always be performed appropriately when the user instructs auto-framing to start at any given timing.
In response to such a demand, Japanese Patent Application Laid-Open No. 2007-189717 discusses a technique in which auto-framing is performed after it has been detected that the participants have sat down. However, if the user instructs auto-framing to start when the participants are already sitting down, the auto-framing cannot be started as the participants continue to be seated. Further, since all participants may not be looking at the camera even when they are seated, the positions of all participants may not be correctly detected.
Furthermore, if the technique is to detect whether the participants have sat down, the technique cannot adapt to a case where there are participants that are standing due to a lack of chairs. Moreover, such a technique cannot apply to a case where all participants are standing, or there are participants sitting in the front row and standing in the back row, such as when taking a group photograph.